diff --git a/scad/jk_extras.scad b/scad/jk_extras.scad
new file mode 100644
index 0000000..ff36374
--- /dev/null
+++ b/scad/jk_extras.scad
@@ -0,0 +1,17 @@
+include <common.scad>;
+IN = 25.4;
+/**
+ * Parametric measurement bar to attach to rails
+ **/ 
+
+module measurement_bar (X = 20 * IN, Y = 16.4, Z = 3, BOLT = 4, BOLT_OFFSET = (3/8) * IN, PROJ_ZERO = 43) {
+	$fn = 50;
+	difference () {
+		rounded_cube([X, Y, Z], d = 5,  center = true);
+		translate([(X / 2) - BOLT_OFFSET, 0, 0]) cylinder(r = BOLT/2, h = Z + 1, center = true);
+		translate([-(X / 2) + BOLT_OFFSET, 0, 0]) cylinder(r = BOLT/2, h = Z + 1, center = true);
+		translate([(X / 2) - PROJ_ZERO, -(Y / 2) + (5 / 2), 0]) cube([0.2, 5, Z + 1], center = true);
+	}
+}
+
+projection() measurement_bar();
\ No newline at end of file